Specifications
Rocket Installation and Operation Manual     
33 
7.4.2  Table of Clearance Reduction Percentages 
Type of shield 
Clearances may be 
reduced by these 
percentages 
Sides 
and rear % 
Top % 
(ceiling) 
Sheet metal, a minimum of 24 
gauge (0.61 mm) in thickness , 
spaced out at least 25 mm (1 in)* 
by non-combustible spacers 
67 50 
Ceramic tiles, or equivalent non-
combustible material, on non-
combustible board spaced out at 
least 25 mm (1 in)* by non-
combustible spacers 
50 33 
Ceramic tiles, or equivalent non-
combustible material, on non-
combustible board, with a 
minimum of 24 gauge (0.61 mm)  
sheet metal backing spaced out at 
least 25 mm (1 in)* by non-
combustible spacers 
67 50 
Brick, spaced out at least 25 mm 
(1 in)* by non-combustible spacers 
50 N/A 
Brick, with a minimum of 24 gauge 
(0.61 mm) sheet metal backing, 
spaced out at least 25 mm (1 in)* 
by non-combustible spacers 
67 N/A 
  * In Canada this space can be 21 mm (7/8 in) 










